Mechanical locking system for floor panels

ABSTRACT

Building panels, especially floor panels are shown, which are provided with a locking system including several separate strip parts connected to the panel edge.

TECHNICAL FIELD

The disclosure generally relates to the field of mechanical lockingsystems for floor panels and building panels. The disclosure showsfloorboards, locking systems and production methods.

FIELD OF APPLICATION

Embodiments of the present disclosure are particularly suitable for usein floating floors, which are formed of floor panels which are joinedmechanically with a locking system integrated with the floor panel, i.e.mounted at the factory, are made up of one or more upper layers of woodor wood veneer, decorative laminate, powder based surfaces or decorativeplastic material, an intermediate core of wood-fibre-based material orplastic material and preferably a lower balancing layer on the rear sideof the core. Floor panels of solid wood or with a surface layer of cork,linoleum, rubber or soft wear layers, for instance needle felt glued toa board, printed and preferably also varnished surface and floors withhard surfaces such as stone, tile and similar materials are included.Embodiments of the disclosure can also be used for joining buildingpanels which preferably contain a board material for instance wallpanels, ceilings, furniture components and similar.

The following description of known technique, problems of known systemsand objects and features of the disclosure will therefore, as anon-restrictive example, be aimed above all at this field of applicationand in particular at panels formed as rectangular floor panels with longand shorts edges intended to be mechanically joined to each other onboth long and short edges.

The long and short edges are mainly used to simplify the description ofembodiments of the disclosure. The panels may be square. Embodiments ofthe disclosure are preferably used on the long edges. It should beemphasised that embodiments of the disclosure can be used in any floorpanel and it may be combined with all types of known locking systemformed on the short edges, where the floor panels are intended to bejoined using a mechanical locking system connecting the panels in thehorizontal and/or vertical directions on at least two adjacent edges.

BACKGROUND

Laminate flooring usually comprise a core of a 6-12 mm fibre board, a0.2-0.8 mm thick upper decorative surface layer of laminate and a0.1-0.6 mm thick lower balancing layer of laminate, plastic, paper orlike material. A laminate surface comprises melamine-impregnated paper.The most common core material is fibreboard with high density and goodstability usually called HDF—High Density Fibreboard. Sometimes alsoMDF—Medium Density Fibreboard—is used as core.

Laminate floor panels of this type have been joined mechanically bymeans of so-called mechanical locking systems. These systems compriselocking means, which lock the panels horizontally and vertically. Themechanical locking systems are usually formed by machining of the coreof the panel. Alternatively, parts of the locking system can be formedof a separate material, for instance aluminium or HDF, which areintegrated with the floor panel, i.e. joined with the floor panel inconnection with the manufacture thereof.

The main advantages of floating floors with mechanical locking systemsare that they are easy to install. They can also easily be taken upagain and used once more at a different location.

DEFINITION OF SOME TERMS

In the following text, the visible surface of the installed floor panelis called “front side”, while the opposite side of the floor panel,facing the sub floor, is called “rear side”. The edge between the frontand rear side is called “joint edge”. By “horizontal plane” is meant aplane, which extends parallel to the outer part of the surface layer.Immediately juxtaposed upper parts of two adjacent joint edges of twojoined floor panels together define a “vertical plane” perpendicular tothe horizontal plane. By “vertical locking” is meant locking parallel tothe vertical plane. By “horizontal locking” is meant locking parallel tothe horizontal plane.

By “up” is meant towards the front side, by “down” towards the rearside, by “inwardly” mainly horizontally towards an inner and centre partof the panel and by “outwardly” mainly horizontally away from the centrepart of the panel.

Related Art and Problems Thereof

For mechanical joining of long edges as well as short edges in thevertical and horizontal direction perpendicular to the edges severalmethods may be used. One of the most used methods is the angle-snapmethod. The long edges are installed by angling. The panel is thendisplaced in locked position along the long side. The short edges arelocked by horizontal snapping. The vertical connection is generally atongue and a groove. During the horizontal displacement, a strip with alocking element is bent and when the edges are in contact, the stripsprings back and a locking element enters a locking groove and locks thepanels horizontally. Such a snap connection is complicated since ahammer and a tapping block has to be used to overcome the frictionbetween the long edges and to bend the strip during the snapping action.

Similar locking systems may also be produced with a rigid strip and theyare connected with an angling-angling method where both short and longedges are angled into a locked position.

It is known that a locking strip may be formed of a separate materialsuch as aluminium or HDF and that such strip may be clamped in undercutgrooves or attached into a horizontally extending groove formed at anedge of a panel by snapping and/or turning. Such systems are describedin WO 94/26999 and WO 03/083234 (Välinge Innovation AB). It is alsoknown that several strip parts spaced form each other may be attached toa long side edge in order to obtain further cost savings.

FIGS. 1 a and 1 b show a known locking system that is locked withangling. The horizontal locking is obtained by a locking strip 6 with alocking element 8 formed at one panel edge 1 that locks into a lockinggroove 14 formed in another adjacent panel edge 1′. The forming of thestrip 6 creates a waste as shown in FIG. 1 b.

FIG. 1 c shows a known locking system with a separate aluminium strip 6attached to a lower part of a panel edge. A part of the strip 6 is bentaround inwardly inclined vertically extending surfaces. Such connectionof the strip 6 to the panel edge is made in a separate operation thanthe machining of the edge. The strip comprises three different crosssection A-A, B-B and C-C. Each cross section comprises the same materialthickness since the strip is formed from a 0.6 mm aluminium sheet. Thelength L of the strip is the same along the width W. The part of thestrip that extends from the edge comprises a small cavity 23, which isformed when a part of the strip body is punched and bent around a paneledge.

FIG. 1 d shows a strip 6, which is attached with snapping into ahorizontally extending groove. This strip is formed by machining and hasthe same cross section along its length.

Such locking systems suffer from several disadvantages. The materialcontent is high due to the design and only limited material savings maybe reached. This fixing of the strip to the edge is rather complicatedand slow.

FIGS. 2 a-2 c show a locking system with a separate displaceable tongue10 a inserted in a horizontally extending displacement groove 10 bformed on the short edge of a panel. The separate tongue is inserted inhigh speed and is mainly used to obtain higher flexibility when thepanels are locked with a vertical snapping. The short side productionspeed is however considerably lower than the long side production speedand conventional inserting methods that are used to insert flexibletongues are not suitable to be used at long edges to insert severalstrips one after each other.

FIG. 3 a shows a conventional panel with a strip 6 that extends alongthe whole long edge. Material savings may be increased if several stripparts 6 are connected on a long side of a panel as shown in FIG. 3 b.

Wood and laminate panels are produced with a production speed on longedges of 1-5 m/sec. This means that 5-25 strip parts must be insertedeach second if, for example, five strip parts per metre are attached atan edge. Known separate strips and fixing methods are not adapted tosuch high-speed production and separate strip parts are not able tocompete with the conventional machining where the strip is machined inone piece with the panel edge.

It would be a major advantage if separate strip parts that comprise lessmaterial and that may be inserted in high speed could be used to replacethe machined strip especially in a long edge locking system.

SUMMARY AND OBJECTS

An overall objective of embodiments of the present disclosure is toprovide an improved and more cost efficient locking system for primarilyrectangular floor panels with long and short edges installed in parallelrows, which allows that the edges may be locked to each with angling,and/or horizontal snapping and/or vertical snapping.

Another specific objective is to provide production method that allowsan efficient high-speed connection of several strip parts into an edgeof a floor panel.

The above objects of embodiments of the disclosure may be achievedwholly or partly by locking systems and floor panels according to thedisclosure. Embodiments of the disclosure are evident from thedescription and drawings.

A first aspect of the disclosure is building panels provided with alocking system for vertical and horizontal locking of a first edge of afirst panel and a second edge of a second adjacent panel. The lockingsystem comprises a tongue and a tongue groove for vertical locking andstrip parts attached to the first edge for horizontal locking. Eachstrip part comprises an upwardly extending locking element configured tocooperate with a downwardly open locking groove formed at the secondedge. The strip part comprises a strip body with an inner part thatextends inwardly from the first edge and at a rear side of the firstpanel and an outer part that extends outwardly from said first edge. Theinner strip part comprises a fixing element that cooperates with adownwardly open fixing groove, formed in the rear side of the firstpanel, and locks the strip part to the first edge in a first horizontaldirection. The strip part comprises a locking protrusion, located abovethe strip body, that locks the strip to the first edge vertically and ina second horizontal direction against a holding protrusion formed at thefirst edge. The strip part is configured to be attached to the firstedge with an essentially horizontal snapping action. The strip partcomprises upper and lower guiding surfaces that are essentially parallelwith the strip part body.

The strip part may comprise a locking protrusion that protrudeshorizontally from the locking element.

The locking protrusion may comprise a sliding surface that duringlocking is in contact with the adjacent edge.

The locking protrusion may be spaced vertically from the strip body.

The strip body may comprise a cavity in the inner part.

The length of the strip part may vary along its width.

The fixing element may comprise a flexible locking part that locksagainst a wall of the fixing groove.

A second aspect of the disclosure is a strip blank comprising severalstrip parts configured to lock panels horizontally and to be fixed to apanel edge by essentially horizontal snapping. The strip blank comprisesat least two strip parts located side by side in at least two parallelrows.

A third aspect of the disclosure is a method to fix several strip partsto an edge of a panel. Each strip part comprises a strip body thatextends inwardly from the edge at the rear side of the panel and isconfigure to lock two adjacent panels horizontally and to be fixed to apanel edge by essentially horizontal snapping. The method comprises thesteps of:

-   -   separating strip parts from a strip blank that comprises at        least two strip parts located side by side in at least two        parallel rows;    -   displacing the strip parts essentially vertically in front of        several hammers;    -   pressing and snapping the strip parts by the hammers to a panel        edge by an essentially horizontal displacement; and    -   activating the hammers one after each other when the panel is        displaced horizontally in relation to the hammers.

A fourth aspect of the disclosure is building panels provided with alocking system for vertical and horizontal locking of a first edge of afirst panel and a second edge of a second adjacent panel. The lockingsystem comprises a tongue and a tongue groove for vertical locking andstrip parts attached to the first edge for horizontal locking. Eachstrip part comprises an upwardly extending locking element configured tocooperate with a downwardly open locking groove formed at the secondedge. The strip part comprises a strip body with an inner part thatextends inwardly from the first edge and at a rear side of the firstpanel and an outer part that extends outwardly from said first edge. Theinner part comprises a fixing element that cooperates with a downwardlyopen fixing groove formed on the rear side of the first panel and thatlocks the strip part to the first edge in a horizontal direction. Thestrip part comprises a locking protrusion, located above the strip bodythat locks the strip part to the first edge vertically against a holdingprotrusion formed at the first edge. The strip part comprises polymermaterial and is formed by injection moulding.

The inner part may comprise several cavities.

The outer part may comprise a cavity.

The cavity may comprise a wall with a wall thickness, which is smallerthan the width of the cavity.

The length of the strip part may vary along its width.

The fixing element may comprise a flexible locking part that locksagainst a wall of the fixing groove.

The building panel may be a floor panel.

A fifth aspect of the disclosure is a strip part, configured to lockpanels horizontally and to be fixed to a panel edge. The strip partcomprises a strip body with an inner part configured to be fixed underthe panel edge and an outer part configured to extend outside the paneledge. The inner part comprises a fixing element configured to lock thestrip part to the panel edge in a horizontal direction. The outer partcomprises a locking protrusion, located above the strip body andconfigured to lock the strip part to the panel edge vertically, and alocking element configured to lock the panels in a horizontal direction.The inner part comprises a cavity formed in the strip body and locatedbetween the fixing element and the locking protrusion.

The fixing element may comprise a flexible locking part that preventsthe strip part to be released from the panel edge by angling.

The flexible locking part may comprise a flexible protrusion extendingalong the fixing element.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will in the following be described in connection toexemplary embodiments and in greater detail with reference to theappended exemplary drawings, wherein:

FIGS. 1 a-d illustrate locking systems according to known technology.

FIGS. 2 a-c illustrate a flexible and displaceable tongue according toknown technology.

FIGS. 3 a-3 b illustrate floorboards with locking systems according toknown technology.

FIGS. 4 a-d illustrate a locking system according to an embodiment ofthe disclosure.

FIGS. 5 a-f illustrate a method to fix the strip to an edge according toan embodiment of the disclosure.

FIGS. 6 a-b illustrate an inserting method according to an embodiment ofthe disclosure.

FIGS. 7 a-d illustrate locking by horizontal snapping according to anembodiment of the disclosure.

FIGS. 8 a-e illustrate locking by horizontal and vertical displacementaccording to an embodiment of the disclosure.

FIGS. 9 a-d illustrate embodiments of the disclosure.

FIGS. 10 a-d illustrate vertical snapping with a separate tongueaccording to an embodiment of the disclosure.

FIGS. 11 a-h illustrate embodiments of the disclosure.

FIGS. 12 a-f illustrate methods according to embodiments of thedisclosure to reduce material content in injection moulded spring parts.

FIGS. 13 a-f illustrate fixing of a strip according to an embodiment ofthe disclosure that comprises a locking extension

FIGS. 14 a-c illustrate a panel with strip parts according to anembodiment of the disclosure.

FIGS. 15 a-d illustrate forming of strip parts by machining according toan embodiment of the disclosure.

FIGS. 16 a-d illustrate forming of strip parts by machining according toan embodiment of the disclosure.

FIG. 17 illustrates a strip blank according to an embodiment of thedisclosure.

FIGS. 18 a-d illustrate different embodiments of the disclosure.

FIGS. 19 a-d illustrate a strip part with a flexible locking part.

FIGS. 20 a-e illustrate fixing of a strip part with horizontaldisplacement and turning.

FIGS. 21 a-d illustrate embodiments of strip parts and fixing of stripparts.

DETAILED DESCRIPTION OF EMBODIMENTS

To facilitate understanding, several locking systems in the figures areshown schematically. It should be emphasised that improved or differentfunctions can be achieved using combinations of the embodiments.

All embodiments may be used separately or in combinations. Angles,dimensions, rounded parts, spaces between surfaces etc. are onlyexamples and may be adjusted within the basic principles of thedisclosure.

FIGS. 4 a-4 d show a locking system according to embodiments of thedisclosure that may be connected with angling. FIG. 4 a shows a strippart 6 comprising a strip body 7 with a fixing element 16 at an outerpart, an upwardly extending locking element 8 at an opposite and outerpart of the strip body and a locking protrusion 19 that preferablyextends essentially horizontally towards the fixing element. The upperpart of the locking element 8 comprises an upper guiding surface 22 andthe strip body 7 comprises a lower guiding surface that facilitates thefixation of the strip 6 to an edge of a first panel 1′ as shown in FIGS.5 a-5 e. The locking protrusion 19 comprises a sliding surface 20 thatfacilitates the insertion of a tongue 10 into a tongue groove 9 duringangling as shown in FIG. 4 b. The panel edge comprises a fixing groove15 that is open towards the rear side of the panel and a holdingprotrusion 18 extending from a lower part of the panel edge. The fixingelement 16 is locked into the fixing groove 15 wherein essentiallyvertical locking surfaces 17 a and 17 b grip behind each other such thatthe strip is locked horizontally to the panel edge. The lockingprotrusion 19 is locked to the holding protrusion 18 vertically whereina lower horizontal locking surface 24 on the locking protrusion 19overlaps an upper horizontal locking surface 25 formed on the holdingprotrusion 18. The locking protrusion 19 comprises preferably a striplocking surface 26 that cooperated with an edge locking surface 27formed on the panel edge and locks the strip part 6 horizontally. Thestrip part is locked horizontally by the active locking surfacescomprising the strip and the edge locking surfaces 26,27 and thecooperating fixing surfaces 17 a, 17 b. The strip part 6 is lockedvertically by lower and upper horizontal locking surfaces 24,25 and bythe upper part of the strip body 28 and the lower part of the edge 29 asshown in FIG. 4 b. The locking element may have a locking angle A ofpreferably about 40-90 degrees against a horizontal plane. A highlocking angle A gives a strong locking but requires a larger lockingdistance LD which is the distance from the vertical plane VP, where theupper edges are in contact, and to the upper part of the locking surface11 of the locking element 8. The strip part comprises an inner part IPthat extends inwardly from the edge at a rear side of the panel edge andan outer part OP that extends from the edge. The strip has a lengthdirection L along the joint, a width W direction in a horizontaldirection perpendicular to the length and a thickness direction Tvertically and perpendicularly to the width W, as shown in FIGS. 4 c and4 d. The thickness of the strip body 7 varies along the width and thisfacilitates the connection of the strip 6 to the edge. The thickness ofthe locking protrusion may also vary. Preferably there is a space Sbetween the holding and locking protrusions 18,19, the strip body 7 andthe locking element 8 as shown in FIG. 4 b. Such a space S may be usedto increase the flexibility of the strip and to facilitate theconnection of the strip to the edge.

FIGS. 5 a-5 e show a method to fix a strip part 6, as described in FIGS.4 a-4 d, to an edge a panel. The panel is during machining of the edgespositioned with the surface pointing downwards. It is preferred that thestrip part is fixed to the panel in the same machining equipment thatforms the edge by rotating tools. This puts special requirement on theinserting method, especially if several strip parts are to be fixed inhigh speed to a long side edge of a panel. The strip parts arepreferably separated from a strip part blank, comprising several stripparts, and displaced vertically to the same level as the panel edge asshown in FIG. 5 a. The strip parts are guided by upper 31 and lower 32guiding rails and pushed by a hammer 30 towards the edge of the pane 1.The strip is connected to the edge with an essentially horizontalsnapping action whereby the fixing element 16 enters partly orcompletely into the fixing groove 15 and the locking protrusion 19overlaps the holding protrusion 18. Such a connection may beaccomplished in high speed and accuracy due to the flexibility of thestrip parts and the precise guidance of the guiding rails. The strippart 6 is after connection displaced laterally in the direction of thelong edges by the panel that is displaced relative the fixing equipment.A final connection of the fixing element 16 into the fixing groove 15 ispreferably made with a wheel 33 that presses the fixing element 16 intothe fixing groove 15 as shown in FIG. 5 e. The fixing element 16 maypress against two opposite walls of the fixing groove 15 as shown inFIGS. 5 d and 5 e. FIG. 5 f shows that bevels or rounded sections 34 a,34 b may be formed on the outer part of the strip part and/or the paneledge in order to facilitate snapping. The strip body 7 may also bethinner at an outer portion than at an inner portion in order tofacilitate snapping and to save material. Bevels or rounded sections mayalso be formed on the outer parts of the holding and locking protrusions18,19. The horizontal locking surfaces may be essentially horizontal orinclined.

FIGS. 6 a and 6 b show a method that may be used to increase theproduction speed such that it may be possible to insert up to 30 stripparts per second and more. The strip parts are in these figures shownwith the locking element 8 pointing upwards. The strip parts 6 areproduced in strip blanks 50 comprising several strip parts attached toeach other in parallel rows. Each row may comprise, for example, 5-10strip parts 6 a-6 e or more as shown in FIG. 6 b. The strips areseparated and moved to a position, preferably vertically, in front ofseveral hammers 30 a-30 e that preferably are located behind each stripin the row. The whole strip part row is inserted by the hammers thatpush the strip parts one after each other towards the panel edge. Thespacing between the strips parts attached to an edge is obtained by thetime difference that the hammer action is activated by a computersystem.

FIGS. 7 a-7 d show that the strip part 6 may be used in locking systemsthat are locked with horizontal snapping where a part of the strip isbent during snapping. The locking protrusion 19 is in this embodimentconnected to the strip body 7. A part of the locking protrusion 19comprises a guiding surface 22 as shown in FIG. 7 d.

FIGS. 8 a-8 b shows that horizontal snapping may be obtained by alocking element 8 that is flexible and bends during locking.

FIGS. 8 c-8 d shows that the locking system may be locked by verticaldisplacement. The locking is accomplished by a flexible locking element8 that bends during the vertical displacement of the panel edges.

FIG. 8 e shows that a part of the locking element 8 and the lockingprotrusion 19 may comprise guiding surfaces 22.

FIGS. 9 a-9 d show that a tongue 10 a may be formed on the first panel 1comprising the strip part 6 and this may be used to facilitate, forexample, a connection with vertical displacement.

FIGS. 10 a-10 d show that the strip part 6 may comprise a pullingextension 13 that pulls a displaceable tongue 10 a into a tongue groove9 during vertical displacement of the panels. The strip part 6 is madeof several cross sections which allowed that guiding rails may belocated on each side of a locking element 8 and a locking protrusion 19.

FIGS. 11 a-11 h show a strip part 6 that is formed by injectionmoulding. This production method makes it possible to form advancedthree dimensional strip parts, which are optimized to save material. Thelocking protrusion 19 is formed as two parts 19 a, 19 b that are spacedfrom each other by a cavity 23. The locking protrusions are connected tothe edges of the locking element 8 as shown in FIG. 11 b. FIGS. 11 c and11 d show that such locking protrusions may comprise a locking extension34 that extends horizontally on each side of the locking element 8 suchthat a cavity 23 a is formed between the extensions. Such extension maycomprise guiding surfaces 31,32 and may be used to guide the strip partwith high precession during production when the strip part is fixed tothe edge as shown in FIG. 11 h.

FIG. 11 e shows a three-dimensional view of a first panel 1 providedwith a strip part 6.

FIG. 11 f illustrates assembling a first panel 1 with a second adjacentpanel.

FIG. 11 c shows that the locking extension 34 or any other part of thestrip may be in contact with an inner wall of the locking groove 14 andthat the panels 1, 1′ are locked with a small space S between the upperedges.

Such locking system may be used in, for example, floors that are glueddown to the sub floor and where a small space gives room for swelling ofthe edges such that the so called “topping” of the edges may be avoided.The strip parts may be used to position floor panels that are glue downand to keep the floor panels in correct position until the glue cures.Only a few strip parts with rather low material content are needed tofacilitate glue down installation.

FIGS. 12 a-12 f show that considerable material reductions may be reachwith a strip part 6 that is three-dimensional and comprises severalcavities 23 a-23 e. The strip part is preferably formed by injectionmoulding of a polymer material that preferably comprises glass fibres.Cavities may be formed in the strip body 23 a, in the locking protrusion23 b, in the locking extension 23 c, in the locking element 23 d and inthe fixing element 23 e. The strip part 6 and the cavities have a lengthL in a direction along the panel edge, a width W perpendicular to theedge and a thickness T in the vertical direction. The length L of thestrip part may vary along the width W, the width W may vary along thelength L and the thickness may vary along the length L.

FIGS. 12 b-12 f show alternative embodiments of a three-dimensionalstrip part 6. The strip part may have several cavities 23 a, 23 f formedin the strip body and/or in the locking protrusion 19 as shown in FIG.12 b. A cavity 23 has preferably a wall 40 with a wall thickness WT thatis smaller than the width of the cavity. Such three dimensional formswill provide considerable cost savings.

FIG. 12 c shows a strip part without a locking extension 34. FIG. 12d-12 f shows that the cavities may have different forms and that thefixing element 16 may be discontinuous. FIG. 12 e show a lockingextension 34 that extends from a middle part of the locking element andthat may be used as guiding according to the principle shown in FIG. 13c.

FIGS. 13 a-13 f show a production method to fix a strip part 6 to apanel edge. The strip parts comprise locking extensions 34 that are usedto guide the strip part during production when the strip part is fixedto the edge of the panel. It is preferred that strip parts are factoryconnected but they may of course be connected to a panel duringinstallation.

The strip parts are displaced in strip blanks towards a displacementdevice 35 that preferably displaces the strip parts vertically to aplane in front of several hammers 30 a-30 c. The strip parts arepreferably also separated from each other and from the blank 50 by thedisplacement device. FIG. 13 a shows a strip blank 50 seen from aboveand FIG. 13 b show the cross section seen from the side. FIGS. 13 c-13 fshow how a strip part is fixed to an edge with essentially a snappingaction when the strip part is guided with high precision by the guidingrails 31, 32 and the locking protrusion 19 with its locking extension34. The strip body 7 may bend but also turn in relation to the lockingprotrusion 19 as shown in FIG. 13 e. The connection between the lockingelement 8 and the locking protrusion may be formed such that a smallturning may take place and this may facilitate the insertion of thestrip and reduce the requirements on the flexibility of the strip body7. A snapping may be obtained even if the strip body 7 is rather rigidand compact since the turning in relation to the locking protrusion 19may be sufficient to allow a snapping action. The locking protrusion 19may also be flexible and bend during the fixation of the strip. Thehammer may comprise a hammer groove 35 as shown in FIG. 13 c and thismay be used to feed and position the strip parts as a complement oralternative to guiding rails. The guiding surfaces may in such anembodiment be somewhat inclined.

FIG. 14 a shows a part of panel with strip parts on the long and on theshort edges. The strip blank comprises preferably the same number ofstrip parts that are connected to an edge. The strip parts may have alength of, for example, about 1-10 cm. Each strip part may be designedto handle a locking force of 10-100 kg. The distance between the stripparts may be 5-20 cm. As a non restricted example it may be mentionedthat a preferred embodiment for a laminate flooring panel with a lengthof about 1.2 m is a panel that comprises 6 strip parts which are about 4cm long and attached with a centre distance of about 20 cm and 10 cmfrom the short edges. Each strip part may be designed such that it has alocking strength of about 60 kg in the horizontal direction. The lockingsystem will have a locking strength of 300 kg/m and this is generallysufficient for a laminate floor.

Strip parts are especially suitable for thicker laminate floorings witha thickness of 9-15 mm, high quality floors with a HPL, plastic orpowder based surface or solid wood floors. The material waste in suchfloors is considerable when a locking system is formed with aconventional machined strip made in one piece with the core. Strip partsare also suitable in so called plastic LVT floors that have an expensiveand soft core, which is not suitable to form a rigid strip.

Parquet flooring with a lamella core are difficult to machine since themachining is made cross wise to the fibre orientation in the lamellas.Strip parts may solve such problems.

The cost to produce a conventional locking system in solid wood floor isvery high and the locking system is generally of a low quality. Thestress on the locking system is very high due to the fact that the edgesand the strip swells, shrinks and bends. Separate strip parts aretherefore especially suitable for this application.

Preferably, the long edges may comprise a locking system with stripparts that may be locked by angling and the short edges may comprise alocking system with cooperating hooks that may be locked by verticalfolding.

Strip parts on any of the opposite long or short edges may be combinedwith all known locking systems on the other opposite edges.

The disclosure does not exclude strip parts attached on both oppositeedges that lock between each or into each other along the joint.

Strip parts may also be used to decrease the friction along the joint inorder to facilitate displacement and horizontal snapping of the shortedges. Plastic material may have a low friction and the contact areabetween the strips and the locking groove 14 in an adjacent edge may bereduced by more than 80% compared to a conventional locking system.

Strip part may also be used to increase friction between long edges andprevent displacement along the edges such that the short edges arelocked horizontally by the long edges. Special protrusions extendingvertically or horizontally from the locking element 8 and/or additionalflexible locking elements that press against the edge of the adjacentpanel 1′, preferably against a part of the locking groove 14, may easilybe formed on the strip parts by injection mouldings.

The strip parts may compose special material such as, for example, waxthat facilitates angling and/or snapping and that reduces the risk forsqueaking sound after installation.

FIGS. 15 a-15 c show that strip blanks 50 and strip parts 6 may beformed by machining of a wood based or plastic based sheet material. Alocking extension 34 may be formed on the strip body that, as shown inthis embodiment, extends horizontally beyond the locking element. FIG.15 d shows that the strip blank 50 may comprise a long extruded ormachined section that is prior to fixing divided into several stripparts 6 a, 6 b by a rotating tool that also forms locking extensions asshown in FIG. 16 c.

FIGS. 16 a-16 d show a production method to form strip blanks 50 andstrip parts 6 by machining of a wood based or plastic based sheetmaterial. The cross sections are formed by rotating tools To1, To2, To3and To4. The sections are thereafter partly separated by a rotating toolToy cross wise and finally separated by a punching tool To6 during thefixing of the strip part 6.

FIG. 17 shows a strip blank 50 with cavities 34 formed by punchingbetween strip parts in order to facilitate the final separation. Thestrip blank 50 comprises at least two strip parts 6 a, 6 b connectedside by side in at least two rows R1 and R2. A strip part may preferablycomprise 5-10 strip parts connected side by side in 5-30 rows.

The strip blanks are preferably designed such that they may be stackedon top of each other.

FIG. 18 a shows a strip part that is connected into a groove formed inan edge. Such known strip part may also be produced in strip blanksaccording to the described production methods. One disadvantage withstrips that are inserted into a horizontally extending groove formed inthe panel edge is that the core must be made of a material withsufficient flexibility. A strip 6 that has a flexible inner part maysolve this problem. Such a strip may be formed as an injection-mouldedcomponent that comprises two cross sections 6 a, 6 b along its length asshown in FIGS. 18 c and 18 d.

FIGS. 19 a-d show a strip part 6 that may be used to, for example, locksolid wood floors that have a considerable swelling and shrinking acrossthe fibre direction. FIG. 19 a shows the strip part 6 seen from aboveand FIG. 19 b shows a cross section. The fixing element 16 comprises aflexible locking part 41 and an undercut 15 a formed in the fixinggroove 15 that prevent the strip part 6 to be disconnected duringtransport and installation. The flexible locking part 41 is prevented toflex vertically upwards by a blocking part 42 when the flexible lockingpart 41 is compressed towards the fixing element 16 and under theblocking part 42. The strip part comprises cavities 23 a, 23 b in itsinner and outer parts with walls 40 a, 40 b that may be essentiallyparallel with the width W of the strip part 6 or they may be rounded orcurved such that the strip part may be flexible along its width W. Thisflexibility may be used to compensate swelling and shrinking of thefloor panel or to compensate production tolerances.

FIGS. 19 c and 19 d show that the strip part may be connected to an edgecomprising the tongue 10 or the tongue groove 9.

FIGS. 20 a-20 e show fixing of a strip part 6 comprising a fixingelement 16 with a flexible locking part 41. The strip part is displacedvertically or horizontally in an angled position towards the panel edgesuch that it reaches a position where the holding and lockingprotrusions 18,19 partially overlap each other and the flexible lockingpart 41 is in contact with an edge part 15 b of the fixing groove 15 asshown by FIGS. 20 a,b. The edge part 15 b comprises preferably anessentially vertical edge. The strip part is thereafter pressedhorizontally inwardly such that the flexible locking part 41 iscompressed and the strip part is angled such that the fixing element 16is inserted into the fixing groove 15 as shown in FIGS. 20 c,d. Theremay be a play 43 b between the fixing groove 15 and the fixing element16 and such a play facilitates fixing with angling. The fixing elementand the fixing groove may have locking surfaces that exceed 90 degrees.FIG. 20 e shows that the pre tension of the flexible locking part 41will press the strip part outwardly such that the locking surfaces 17are in contact and the strip part will be firmly connected to the paneledge.

The strip parts 6 may be produced and delivered as individual elements.They may have a form that makes it possible to position the individualstrip parts side by side automatically by shaking, rotation etc. asshown in FIG. 21 a.

The strip parts may have one or several flexible locking parts 41 thatmay be formed in the fixing element as snapping tabs or snapping hooks.The flexible locking parts are preferably formed as flexible protrusions44 a, 44 b extending and flexing along the fixing element 16 and in thelength direction L of the strip part 6. A pair of flexible protrusions44 a, 44 b may be oriented towards each other as shown in FIG. 21 a oraway from each other as shown in FIG. 21 b. The cooperating blockingpart 42 is preferably located opposite an outer part of a flexibleprotrusion.

FIG. 21 b shows that flexible parts or protrusions 44 c,d withcooperating blocking parts 42 b may also be formed on the holdingprotrusion 18 and this allows that the strip part 6 may be connected toa panel edge with vertical snapping. Flexible parts or protrusions 44 ethat lock against a wall of the locking groove 14 and cooperatingblocking parts 42 c may also be formed on the locking element 8 and thismay be used to prevent the locking element 8 to snap out from thelocking groove 14 in order to increase the locking strength. Allembodiments may be partly or completely combined with each other.

Strip parts 6 a-f may be fixed to the edge by a displacement along thepanel edge. A pressure force P1 may be used to displace the strip partsalong the edge until they reach an end position where they are pressedhorizontally P2 and vertically P3 such that they may be connected to thepanel edge as shown in FIGS. 20 a-e. Wheels and rulers may be used todisplace and angle the strip parts into the required positions. Themechanical connection may be combined with glue.

FIG. 21 d shows that a strip part 6 with a flexible locking part 41 maybe connected to a panel edge with an essentially horizontal snap action.

1. Building panels provided with a locking system for vertical andhorizontal locking of a first edge of a first panel and a second edge ofa second adjacent panel, said locking system comprises a tongue and atongue groove for vertical locking and strip parts attached to the firstedge for horizontal locking, each strip part comprises: an upwardlyextending locking element configured to cooperate with a downwardly openlocking groove formed at the second edge; a strip body with an innerpart that extends inwardly from the first edge and at a rear side of thefirst panel and an outer part that extends outwardly from said firstedge, the inner part comprises a fixing element that cooperates with adownwardly open fixing groove, formed on the rear side of the firstpanel, and locks the strip part to the first edge in a first horizontaldirection; a locking protrusion, located above the strip body, thatlocks the strip part to the first edge vertically and in a secondhorizontal direction against a holding protrusion formed at the firstedge; and upper and lower guiding surfaces that are essentially parallelwith the strip part body, wherein the strip part is configured to beattached to the first edge with an essentially horizontal snappingaction.
 2. The building panels as claimed in claim 1, wherein thelocking protrusion protrudes from the locking element.
 3. The buildingpanels as claimed in claim 1, wherein the locking protrusion comprises asliding surface that during locking is in contact with the second edgeof the second adjacent panel.
 4. The building panels as claimed in claim1, wherein said locking protrusion is spaced vertically from the stripbody
 5. The building panels as claimed in claim 1, wherein the stripbody comprises a cavity in the inner part.
 6. The building panels asclaimed in claim 1, wherein the length of the strip part varies alongits width.
 7. The building panels as claimed in claim 1, wherein thefixing groove comprises a first wall, a bottom wall and a second wall,wherein the fixing element locks the strip part to the first edge in afirst horizontal direction with the first wall, wherein the fixingelement further comprises a flexible locking part that locks against thesecond wall of the fixing groove.
 8. A strip blank comprising severalstrip parts configured to lock panels horizontally and to be fixed to apanel edge by essentially horizontal snapping, wherein the strip blankcomprises at least two strip parts located side by side in at least twoparallel rows.
 9. A method to fix several strip parts to an edge of apanel, each strip part comprises a strip body that extends inwardly fromthe edge and at the rear side of the panel and is configured to lock twoadjacent panels horizontally and to be fixed to a panel edge byessentially horizontal snapping, wherein the method comprises the stepsof: separating strip parts from a strip blank that comprises at leasttwo strip parts located side by side in at least two parallel rows;displacing the strip parts essentially vertically in front of severalhammers; pressing and snapping the strip parts by the hammers to a paneledge by an essentially horizontal displacement; and activating thehammers one after each other when the panel is displaced horizontally inrelation to the hammers.
 10. Building panels provided with a lockingsystem for vertical and horizontal locking of a first edge of a firstpanel and a second edge of a second adjacent panel, said locking systemcomprises a tongue and a tongue groove for vertical locking and stripparts attached to the first edge for horizontal locking, each strip partcomprises: an upwardly extending locking element configured to cooperatewith a downwardly open locking groove formed at the second edge; a stripbody with an inner part that extends inwardly from the first edge and ata rear side of the first panel and an outer part that extends outwardlyfrom said first edge, the inner part comprises a fixing element thatcooperates with a downwardly open fixing groove, formed on the rear sideof the first panel, and that locks the strip part to the first edge in ahorizontal direction, the inner part comprises a cavity; a lockingprotrusion, located above the strip body, that locks the strip part tothe first edge vertically against a holding protrusion formed at thefirst edge; and polymer material and is formed by injection moulding.11. The building panels as claimed in claim 10, wherein the inner partcomprises several cavities.
 12. The building panels as claimed in claim10, wherein the outer part comprises a cavity.
 13. The building panelsas claimed in claim 10, wherein the cavity comprises a wall with a wallthickness, which is smaller than the width of the cavity.
 14. Thebuilding panels as claimed in claim 10, wherein the length of the strippart varies along its width.
 15. The building panels as claimed in claim10, wherein the fixing groove comprises a first wall, a bottom wall anda second wall, wherein the fixing element locks the strip part to thefirst edge in a first horizontal direction with the first wall, whereinthe fixing element further comprises a flexible locking part that locksagainst the second wall of the fixing groove.
 16. The building panels asclaimed in claim 10, wherein the building panel is a floor panel.
 17. Astrip part, configured to lock panels horizontally and to be fixed to apanel edge, comprising a strip body with an inner part configured to befixed under the panel edge and an outer part configured to extendoutside the panel edge, wherein the inner part comprises a fixingelement configured to lock the strip part to the panel edge in ahorizontal direction, wherein the outer part comprises a lockingprotrusion, located above the strip body and configured to lock thestrip part to the panel edge vertically and a locking element configuredto lock the panels in a horizontal direction, and wherein the inner partcomprises a cavity formed in the strip body and located between thefixing element and the locking protrusion.
 18. The strip part as claimedin claim 17, wherein the fixing element comprises a flexible lockingpart that prevents the strip part to be released from the panel edge byangling.
 19. The strip part as claimed in claim 17, wherein the flexiblelocking part comprises a flexible protrusion extending along the fixingelement.